1. Field of the Invention
The invention relates generally to downhole locking devices and blanking plugs. In specific aspects, the invention relates to devices and methods for sand control in association with these devices.
2. Description of the Related Art
Locking devices, or locks, are used to anchor a well tool at a particular location within a well conduit, such as a tubing string. A locking device is described in U.S. Pat. No. 4,510,995 entitled “Downhole Locking Apparatus” which was issued to Krause, Jr. et al. and is owned by the assignee of the present application. That patent is incorporated herein by reference. A locking device of this type is also available commercially as the Extreme SUR-SET® locking system sold by Baker Oil Tools, 6023 Navigation Blvd., Houston, Tex. 77253. This locking device has a set of radially expandable locking dogs that seat within a complimentary nipple or profile in the tubing string. The lock also incorporates a no-go shoulder to help ensure proper positioning in the tubing string. The lock is run into the tubing string using a running tool, which also sets the lock by expanding the locking dogs into the matching nipple. The running tool is then removed. When it is desired to remove the lock, a retrieval tool is run into the tubing string, engages the lock and retracts the locking dogs. The retrieval tool and lock may then be removed from the wellbore.
Safety valves and check valves are typically anchored with a lock. Alternatively, a lock may serve as a blanking plug to establish a fluid seal within the tubing string. One example is the Extreme SUR-SET® Model H blanking plug available from Baker Oil Tools, 6023 Navigation Blvd., Houston, Tex. 77253. When in place, the blanking plug blanks off all pressure from above or below the lock. Blanking plugs are useful for pressure testing the tubing string or to abandon certain zones within a well.
Certain blanking plugs use a removable prong that is inserted into the plug to equalize the pressure across the plug and to complete the fluid seal. A pressure equalization port is disposed through the housing of the plug. After setting the plug portion and prior to installation of the prong, fluid containing sand or other solid particles may enter this port and cause clogging of the interior. As a result, it may be difficult to insert or secure the prong within the plug portion. The present invention addresses the problems of the prior art.